In emergency medical service applications, air-ambulances, such as helicopters, have been used for emergency transfer and treatment of patients. Often such service involves transporting multiple patients and patients requiring immediate attention and treatment.
Various methods have been employed to transport patients in a helicopter. For example, in various medical systems, the patient is placed on a stretcher or litter which is attached to the floor or a fixed bench within the helicopter. These systems have proved unsatisfactory in several respects. First, in order for the EMS attendants or paramedics to work on the patient, they must get down on the floor, creating an awkward working posture. Second, the interior space is generally cramped and the attendants or paramedics in their crouched position generally take up more space than they would while sitting upright.
In order to alleviate the problems associated with the above referenced systems, several medical systems have been employed in helicopter interiors which place the patient(s) at a more comfortable level for the attendants or paramedics to work, as well as freeing up floor space within the emergency vehicle interior. These systems are, however, quite limited in usefulness and suffer from other considerable drawbacks. For example, numerous helicopters and/or fixed wing aircraft merely employ tiers of stationery litter racks. There is generally no mechanism to assist in the loading of the upper racks, nor any means for tilting the rack or racks in various orientations. Many of these systems also require an unacceptable level of manpower, physical effort and loading time which may be crucial. Illustrative are the litter rack systems disclosed in U.S. Pat. Nos. 2,370,402, 2,473,364, 2,480,322 and 3,358,300.
In U.S. Pat. No. 3,605,136, a powered litter rack is disclosed which could also be mounted in an air-ambulance. In the noted system, a pair of vertical frames are mounted within the vehicle, with endless chains provided along each side of the frames. The frames are provided with space brackets for supporting the handles of emergency litters. One or more litters can be positioned within the frames, and the endless chains are used to elevate the litter(s) in a vertical direction. The frames can also be operated independently to raise or lower either end of the litter(s) for medical treatment. A major drawback of the noted system is the use of a complex system of chains, gears and worms. This system also requires considerable space for operation and is, in general, unacceptably heavy for aircraft use.
In U.S. Pat. No. 4,378,128, another litter rack system is disclosed for elevating and supporting a pair of litters. In the noted system, a pair of actuators are provided on each end of the mechanism for raising and positioning the litter. The system is, however, manually operated, limited to two litters and also requires considerable space in the aircraft interior.
In U.S. Pat. No. 4,783,025, a powered litter rack system is disclosed for elevating and supporting a single litter. In general, the system employs a pair of vertical mounts positioned along one side of a litter pallet or platform. The mounts include a linear actuator and bearing blocks. Each bearing block has an outwardly extending arm, which is attached to the underside of the platform. The linear actuators are arranged to raise or lower the bearing blocks so as to vertically move the platform. Individual controls are also provided for independently operating each of the mounts, so that the platform can be raised horizontally with the head or foot section lowered or raised as desired. This system also suffers from various drawbacks.
First, the system is not multi-tiered and, hence, can only support one patient. Second, the linear actuator and all pertinent related components are designed external, with beating rings sliding on vertical rods which provide vertical movement. The bearing ring/rod combination could therefore be subjected to sudden stoppage by foreign objects. Third, the bearing ring and rod assembly could also produce contamination and result in a less sterile environment due to lubrication requirements.
It is therefore an object of the present invention to provide a powered multi-tiered litter rack system for use in an emergency medical vehicle, such as a helicopter, which is self-contained, space efficient, requires less moving parts, is more resilient during operation and emergency load conditions, and permits free movement without fear of loose clothing or foreign objects binding or stopping the lift motion.